1. Field of the Invention
This invention relates to .alpha.-(3-(1-phenylethenyl)phenyl)propionic acid or or its ester which is represented by the following formula (II) and further relates to a method for producing .alpha.-(3-benzoylphenyl)propionic acid or its ester which is represented by the following formula (I) using the former new compound as an intermediate. ##STR1##
.alpha.-(3-(1-phenylethenyl)phenyl)propionic acid and its ester (formula II) are intermediates used for economically preparing .alpha.-(3-benzoylphenyl)propionic acid (tradename: ketoprofen) which is represented by the following formula (I-a) and is used as a medicine for the relief of pain, fever and inflammation. ##STR2## wherein R is an alkyl group having 1 to 4 carbon atoms.
The above ester of the formula (I-b) is easily hydrolyzed to produce .alpha.-(3-benzoylphenyl)propionic acid.
2. Description of the Prior Art
With regard to the preparation of ketoprofen, various methods have been proposed. Typical methods of them are exemplified as follows:
(1) Ketoprofen is prepared in a high yield by reacting 3-vinylbenzophenone with carbon monoxide in dilute hydrochloric acid in the presence of a palladium catalyst (U.S. Pat. No. 4,329,507). ##STR3##
(2) 4-Acetylbenzophenone is reacted with chloroform in a basic condition in the presence of tertiary ammonium salt to obtain .alpha.-arylpropenoic acid and it is then subjected to catalytic hydrogenation reduction in the presence of palladium-carbon catalyst to obtain ketoprofen (Japanese Laid-Open Patent Publication No. 55-7225). ##STR4##
(3) 3-Benzoylpropiophenone is reacted with orthomethyl formate in the presence of thallium nitrate to produce the methyl ester of ketoprofen (British Patent No. 2,019,393). ##STR5##
(4) 3-Benzylacetophenone is reacted with ethyl chloroactate in the presence of a strong base to produce glycidic acid ester. This compound is then treated with an aqueous solution of sodium hydroxide to obtain a hydrolyzed and decarboxylated product of .alpha.-(3-benzylphenyl)propionaldehyde and it is further oxidized with potassium permanganate to obtain the ketoprofen (Japanese Laid-Open Patent Publication No. 55-36450). ##STR6##
In both the above methods (1) and (2), the numbers of reaction steps are small and the aimed product can be obtaine in high yields. It cannot be said, however, that the synthesis of starting materials is easy.
With regard to the method (3), even though the reaction process is short, it cannot be said that the preparation of the raw material is easy and safe because the toxic thallium compound is used. Furthermore, it cannot be said that the starting material used in the method (4) is easily available. Accordingly, these methods (1) to (4) are not satisfactory in view of industrial production.